This register contains user programmable bits used to select AES key usage and set the read/write protection for other eFUSE registers.
Table: eFUSE Control Register Bit (FUSE_CNTL) Description
provides bit descriptions and recommended settings.
Table 4:
eFUSE Control Register Bit (FUSE_CNTL) Description
|
Bit
|
Bit Name
|
Description
|
Recommended Setting
|
|
0
|
R_DIS_Key
|
When programmed to 1, this bit disables the CRC check that verifies the AES key and programming of the AES key.
|
Yes
(program to 1)
|
|
1
|
R_DIS_USER
|
When programmed to 1, this bit disables reading of the FUSE_USER user code. This does not disable reading the user code through EFUSE_USR component, although it disables reading the user code through the JTAG port.
|
No
(keep at 0)
|
|
2
|
R_DIS_SEC
|
When programmed to 1, the bit disables reading of the FUSE_SEC security settings via JTAG.
|
Yes
(program to 1)
|
|
3–4
|
Reserved
|
Reserved
|
–
|
|
5
|
W_DIS_CNTL
|
When programmed to 1, this bit disables programming of the FUSE_CNTL bits.
RECOMMENDED:
Program this bit to
1
after programming the FUSE_CNTL register bits to prevent unintended changes to the FUSE_CNTL eFUSE bits.
|
Yes
(program to 1)
|
|
6
|
R_DIS_RSA
|
When programmed to 1, this bit disables reading of the FUSE_RSA authentication key.
|
Yes
(program to 1)
|
|
7
|
W_DIS_KEY
|
When programmed to 1, this bit disables programming of the AES key and CRC check that verifies the key.
RECOMMENDED:
Program this bit after programming the key to prevent unintended changes/corruption to the eFUSE AES key value.
|
Yes
(program to 1)
|
|
8
|
W_DIS_USER
|
Disable programming of the FUSE_USER user code.
|
No
(keep at
0
)
|
|
9
|
W_DIS_SEC
|
When programmed to 1, this bit disables programming of the FUSE_SEC register bits.
RECOMMENDED:
Program this bit after programming the FUSE_SEC register to prevent unintended changes/corruption to the FUSE_SEC register.
|
Yes
(program to 1)
|
|
10–14
|
Reserved
|
Reserved
|
–
|
|
15
|
W_DIS_RSA
|
When programmed to 1, this bit disables programming of FUSE_RSA authentication key.
|
Pending customer security requirements
|
|
16
|
W_DIS_USER_128
|
When programmed to 1, this bit disables programming of FUSE_USER_128 user code.
|
–
|
|
17–23
|
Reserved
|
Reserved UltraScale bits extend through bit 20 and reserved UltraScale+ bits extend through bit 23.
|
–
|